Former U.S. Vice President Walter Mondale and former Minnesota Supreme Court Chief Justice Kathleen Blatz are promoting Lawyers United for All Families, which is working to defeat the proposed constitutional amendment that would ban gay marriage.

The two co-signed a letter urging colleagues to vote no on the amendment question, which will be on November's state-wide ballot.

"Our constitution is a hard-earned gift from those who preceded us, and an enduring promise to those who will follow us," Mondale said in a statement. "It should be used to protect individual liberty, not to take it away."

Said Blatz: "At this crossroads in Minnesota’s history we must not allow our state’s constitution to get caught up in the prevailing winds of the day. We may disagree on how best to recognize committed same-sex couples, but I believe quite firmly that legislating this issue by constitutional amendment is both inappropriate and a threat to the legacy of our state."